In ballooning or catheter examinations inside the heart, for example, the balloon catheter or any other catheter is advanced or retracted by means of a so-called guide wire inside a guiding catheter previously introduced in the patient. In the monorail type of balloon catheters, the guide wire exits from the wire-receiving lumen of the balloon catheter about 10 to 30 cm proximally of the baloon (FIG. 1) and then extends outside, but in parallel with, the balloon catheter shank, within the guide catheter up to the proximal end thereof outside the patient so that the surgeon can hold the shank of the balloon catheter and the guide wire side by side (or one behind the other in non-monorail systems) for manipulation by his/her hands at the proximal end of the guide catheter.
As the ballooning or other catheter treatment proceeds, the catheter may have to be withdrawn completely from the guide catheter for replacement, for example. When this is done, it is important for the guide wire to be held--despite the withdrawal of the balloon catheter--in the position it has attained in order to keep the attained location within reach. Withdrawing the (balloon) catheter is unproblematic, initially, and is accomplished by simply holding the guide wire by one hand and withdrawing the shaft of the (balloon) catheter by the other hand until the guide wire entry opening in the (balloon) catheter shank has reached the proximal end of the guide catheter. In the final portion of the distance, in which the guide wire extends within the shank (e.g. of a balloon catheter used in angioplasty), this process calls for a special technique to keep the wire from being accidentally withdrawn together with the (balloon) catheter. What this means is that the guide wire (because of its low resistance to buckling) has to be advanced step by step against the (balloon) catheter to the extent that the distal end of the latter (with the guide wire centrally extending therethrough) is withdrawn from the guide catheter. This procedure is relatively cumbersome and time consuming and requires the surgeon to pay utmost attention to what he/she is doing.